Drive for surface-finishing tool



0. D. SOGGE Jan. 23, 1968 DRIVE FOR SURFACE-FINISHING TOOL Filed Oct. 21, 1965 INVENTOR OLIN D. SOGGE United States Patent Ofifice 35%,525 Patented Jan. 23, 1968 3,364,625 DRIVE FOR SURFACE-FINISHING TOOL Olin D. Sogge, Sioux City, Iowa, assignor to Aiher tson 8; Company, 11m, Sioux City, Iowa, a corporation of Iowa Filed st. 21, 1965, Ser. No. 599,121 6 Claims. (Cl. 51-119) This invention relates to surface-finishing devices and will be described for purposes of illustration with reference to its application to a disc sander.

It has been found that a sanding disc, if allowed to rotate freely about its own axis while being given an orbital movement, will have a rotation induced thereinto by the frictional forces developed between the disc and the surface being abraded. This induced rotation will be in a direction opposite to the orbital movement, but, most importantly, will cause the disc to traverse the surface being abraded in a continually changing path so that grooving of the surface is eliminated and a desired matte finish is produced. The stock removal per mm time produced by the induced rotation, however, is smaller than that produced by a direct drive and hence a direct rotation of the abrasive disc with the drive motor for the device is desirable for the coarse work. Fast stock removal and a matte finish can be obtained, of course, with the aid of two separate sanders, one having a disc permanently and rigidly connected to a drive motor for the fast stock removal, and the other having a disc freely rotatable about an axis eccentric to the axis of the motor for the matte finish. This, however, results in a duplication of expense insofar as the motor and sanding disc are concerned.

It has been proposed to provide a manually operable means for selectively interlocking a sanding disc with the output of a drive motor, or allowing it to rotate freely about an axis eccentric to that of the motor axis. Such manually operated connecting means required that the motor be stopped and the manual connection be operated while the motor was stopped.

An object of this invention is the provision of a drive means for a disc-shaped surface finishing device wherein means are provided for either automatically connecting the disc directly to the drive motor of the device for rotation thereby, or allowing the disc to rotate freely in an orbital path about the drive motor axis.

As a more specific object, this invention has within its purview the provision of a drive means for the disc of a surface-finishing device wherein a one-Way clutch is used automatically to disconnect the disc from the motor of the device when the relative speeds between the motor and disc are reversed.

It is also an object of this invention to provide a reversible fluid-operated motor for a disc-shaped surface-finishing device, with a one-way drive means disposed between the motor and disc-shaped surface for automatically disconnecting the motor from the disc-shaped surface in one direction of rotation of the motor to allow an orbital movement to be imparted to the disc-shaped surface by contact between said surface and the surface being finished.

These and other objects of this invention will become apparent from the detailed description when taken together with the accompanying drawings in which;

FIG. 1 is a fragmentary plan view of a disc sander incorporating the present invention;

FIG. 2 is a side elevational view, partly in section, of the sander of FIG. 1, and

FIG. 3 is a greatly enlarged cross-section taken through the one-way clutch for the sander of this invention, the section being fragmentary and taken along line 33 of FIG. 2.

By way of general description, this invention takes advantage of the automatic disconnection of a drive through a one-way clutch when the drive member rotates more slowly than the driven member, or rotates in an opposite direction from that of the driven member. In the present invention, a reverse rotation of the drive member relative to the driven member is produced, and to this end a reversible motor is used with the one-way clutch. As an illustrative example, a portable reversible air motor will be described herein, although it is not necessary that the motor be portable nor air driven for the successful operation of this invention. For a fast and relatively coarse stock removal, the direction of drive of the motor which causes an engagement of the one-way clutch, is used, and when it is desired to produce a relatively fine matte finish, the direction of drive of the motor is reversed, merely by operating a reversing valve, and the one-way clutch is automatically released, whereupon the disc is then allowed to rotate freely about its own axis in an orbital movement about the motor axis.

Referring now to FIG. 1 for a detailed description of the invention, the portable sander is comprised of a disc 16, an air motor 11, a handle 12 and an air conduit 13 leading to a pump shown diagrammatically at 14, or other air compressor. Air motor 11 may be a commercially available vaned motor which is rotated by the impingement of a stream of air upon radially disposed vanes operating in appropriately formed cavities in the motor housing. A manually operable reversing valve 15 may be disposed in the handle 12 in communication with conduit 13 and with oppositely directed conduits 18 and 19 which direct the air from conduit 13 to opposite sides of the vanes (not shown) of the motor 11. Said valve 15 determines whether the disc 10 will be driven directly by the motor 11 or will be allowed to rotate freely with a planetating or orbital movement. An on-oif valve 16 controls admission of air from conduit 13 to valve 15 and is used to start and stop the motor 10 in whatever direction it has been set to operate by the reversing valve 15.

Referring to FIG. 2, the sanding disc 10 may be of any well-known form and may be provided with an abrasive paper or cloth 17 suitably secured or adhered to the flat disc-shaped bottom surface of the disc 10. Alternatively, disc 10 may be a wheel made from a bonded abrasive. Said disc 14} is appropriately secured for rotation with a concentrically disposed screw 20 which is threadedly received in correspondingly threaded opening 21 in a short shaft 22. Said shaft has a shoulder 23 against which bears the inner race of a ball bearing 24, the outer race of which is received in a counterbore 25 in an opening 26 in the enlarged end 27 of motor shaft 23. The outer race of ball bearing 24 is pressed into the counterbore 25', and the inner race of the ball bearing is held against shoulder 23 by a snap ring 29.

A one-way clutch 3G is interposed in the opening 26 between the Walls defining said opening and short shaft 22. Said clutch is adapted to lock short shaft 22 to motor shaft 28 when said motor shaft rotates in one direction, and to disconnect said short shaft from the motor shaft when the latter rotates in the opposite direction. As shown more clearly in the enlarged view or" the clutch in FIG. 3, said clutch is comprised of a cam ring 31 press-fitted into opening 26, or otherwise secured for rotation with the enlarged end 27 of shaft 28, and of a plurality of rollers 32 interposed between the cam ring 3 1 and the surface of short shaft 22. A roller cage 33 serves to maintain rollers 32 in spaced relation to one another, and resiliently biased means at, which is not shown in detail, serves to urge said rollers along the cams 35 of cam ring 31 in a direction to wedge the rollers between said cam ring 31 and the short shaft 22. The roller-andcam form of one-Way clutch illustrated is but one of a number of forms of commercially available one-way driving devices which may be used to drive short shaft 22 3 from shaft 28, and hence it is understood that the rollerand-cam form is shown merely to illustrate a preferred form of the invention.

The axis of short shaft 22 is parallel with, and offset from, the axis of motor shaft 28 by an amount shown as X in FIG. 2. Shaft 28 is appropriately mounted in bearings 35, 37 in housing 38 for motor 11, and to minimize vibration resulting from the eccentric disposition of disc 10, enlarged end 27 of shaft 28 is formed in a manner to provide a counter-balance for the eccentrically mounted disc.

The on-off valve 16 is a simple reciprocating bicycletype valve having a seat 39, a valve element at), and a spring 41 bearing against an adjustable screw 42, so that valve 16 is normally held against its seat 39 to close the passage from conduit 13 and shut off iiow of air to the motor 11. A thumb-operated lever 43 contacts the outer end of valve 16 to press said valve against the action of the spring 41 and thereby move the valve off its seat 39 to establish communication between the motor and the air conduit 13. The reversing valve 15 may be of any standard form and hence is not shown in detail, suffice it to say that it is controlled by an external lever 44 and serves to direct the air coming from valve 16 at will to either conduit 18 or conduit 19.

It may be observed from FIG. 3 that when the enlarged end 27 of shaft 28 is rotated in a clockwise direction as viewed in FIG. 3 while disc it rests upon the surface to be abraded, the rollers 32 will be urged against the cams 35 to wedge said rollers between the cams and the outer surface of the short shaft 22, thereby establishing a direct drive between the cam ring 31 and shaft 22. Inasmuch as cam ring 31 is pressed into and rotatable with the enlarged end 27 of shaft 28, said short shaft 22 will be rotated with and driven by motor shaft 28. Disc therefore will rotate at the same speed as shaft 28 but with an eccentric motion and will provide a fast and relatively coarse abrading action. Due to the eccentric motion, grooving of the work piece will be greatly minimized. During such rotation the motor may be stopped by releasing lever 43 to allow spring 41 to seat valve element at on its seat 39. Pressing down upon lever 43, as viewed in FIG. 2, will open the valve, that is, will unseat valve element 45 and start motor 11 to rotating again. When a fine abrading action is desired, lever 44 of the reversing valve is appropriately turned to cause the air from conduit 13 to enter the conduit 18 or 19 not then in communication with conduit 13, which will cause a reverse rotation of motor shaft 28 from the direction in which it had previously been rotating. With such reverse rotation of shaft 28, and with disc 1% resting upon the surface to be abraded, cam ring 31 will be rotated in a counter-clockwise direction relative to short shaft 22, as viewed in FIG. 3, thereby causing rollers 32 to be urged away from the earns 35 and thereby disconnecting short shaft 22 from cam ring 31. When shaft 22 is disconnected, it is free to rotate at the speed dictated by the frictional forces developed between the abrasive surface 17 on disc 10 and the surface to be abraded. Disc 1! thus will be rotated in the opposite sense from its direct drive and at a slower speed than the motor shaft 28 to result in a slower removal of stock and a finer or matte-surface finish. Insofar as the abrasion of the surface to be finished is concerned, it is immaterial in which sense the disc 1t rotates and therefore the objective of the two-speed drive, one a direct drive from the motor and the other a drive dictated by the forces of friction developed between the disc and the surface being abraded, is very simply achieved merely by reversing the direction of the motor. Furthermore, inasmuch as no inter-engaging toothed devices are employed to effect a change from a direct drive to an induced drive, the change can be made very quickly and very simply, merely by shifting lever 44. This can be done before motor 11 stops and Without raising disc 19 from the surface being abraded.

Although an air motor has been disclosed as a means for driving disc 16, it is understood that other types of motor may be used, if desired or more convenient. lt likewise is not material to this invention that the motor and disc be direct-connected, since it is entirely feasible that the motor be located some distance from the disc and be connected thereto by a flexible drive through an eccentric drive such as 2-7 in FIG. 2.

The foregoing description, therefore, is to be considered as illustrative of the preferred form of the invention and the scope of the invention is not to be limited thereto but is to be determined by the appended claims.

I claim:

1. A surface-finishing device comprising a drive shaft, a driven element connected to receive drive from the drive shaft, a driven shaft mounted for rotation in said driven element about an axis eccentric to the axis of the drive shaft, one-way clutch means connecting the driven shaft to the driven element, a surface-finishing tool connected to be driven by the driven shaft, and means for selectively driving the drive shaft in one direction or in an opposite direction.

2. A surface-finishing device as described in claim 1, said means for selectively driving the drive shaft comprising a reversible motor, control means for determining the direction of drive of said motor, and control means for starting and stopping said motor.

3. A surface-finishing device as described in claim 1, said surface-finishing tool comprising a sanding disc.

4. A surface-finishing device as described in claim 1, said driven element having a bore therein disposed eccentrically to the axis of the drive shaft, said driven shaft being received in said bore, and said one-way clutch being disposed in said bore.

5. A surface-finishing device as described in claim 1, said driven element having a bore therein disposed eccentrically to the axis of the drive shaft and a counterbore, said driven shaft being received in said bore and counterbore, said one-way clutch being disposed in said bore, and an anti-friction bearing in the counterbore supporting the driven shaft in the driven element.

5. A surface-finishing device as described in claim 1, said driven element having a bore therein disposed eccentrically to the axis of the drive shaft, said driven shaft being of smaller diameter than said bore, means support ing said driven shaft in said bore in concentric relation thereto to define an annular space between the driven shaft and driven element, and said 0r1e-way clutch comprising a cam ring in said annular space, rollers interposed between said cam ring and shaft, and means resiliently urging said rollers to contact said cam ring and driven shaft.

References ited UNITED STATES PATENTS HAROLD D. \VH'ITEHEAD, Primary Examiner. 

1. A SURFACE-FINISHING DEVICE COMPRISING A DRIVE SHAFT, A DRIVEN ELEMENT CONNECTED TO RECEIVE DRIVE FROM THE DRIVE SHAFT, A DRIVEN SHAFT MOUNTED FOR ROTATION IN SAID DRIVEN ELEMENT ABOUT AN AXIS ECCENTRIC TO THE AXIS OF THE DRIVE SHAFT, ONE-WAY CLUTCH MEANS CONNECTING THE DRIVEN SHAFT TO THE DRIVEN ELEMENT, A SURFACE-FINISHING TOOL CONNECTED TO BE DRIVEN BY THE DRIVEN SHAFT, AND MEANS FOR SELECTIVELY DRIVING THE DRIVE SHAFT IN ONE DIRECTION OR IN AN OPPOSITE DIRECTION. 